Most current mechanical watches include a balance/balance spring type resonator, which forms the time base of the watch, and an escapement mechanism, generally a Swiss lever escapement, which fulfils two main functions:                maintaining the back-and-forth motions of the resonator;        counting these back and forth motions.        
The escapement must be robust, resist shocks, and be devised to avoid jamming the movement (overbanking).
A mechanical resonator combines at least one inertial element and one elastic return element. In the sprung-balance, the balance spring acts as the elastic return element for the inertial element formed by the balance.
The balance is conventionally guided in rotation by pivots which rotate in smooth ruby bearings. This produces friction, and therefore energy losses and disturbances in operation, which it is sought to remove. The losses are characterized by the quality factor, Q. It is sought to maximise the Q factor.
The Swiss lever escapement has low energy efficiency (around 30%). This low efficiency is due to the fact that the escapement motions are jerky, there are “drops” (runs to the banking to accommodate machining errors) and also because several components transmit their motion via inclined planes which rub against one another.
EP Patent Application 2908189 in the name of ETA Manufacture Horlogère Suisse discloses a mechanism for synchronizing two timepiece oscillators with a gear train, wherein a timepiece regulating mechanism comprises, mounted to move in at least a pivoting motion with respect to a plate, an escape wheel arranged to receive a drive torque via a gear train, and a first oscillator comprising a first rigid structure connected to the plate by first elastic return means. This regulating mechanism includes a second oscillator, which comprises a second rigid structure, which is connected to the first rigid structure by second elastic return means, and which includes bearing means arranged to cooperate with complementary bearing means comprised in the escape wheel, synchronizing the first oscillator and the second oscillator with the gear train.
EP Patent Application 3054358 in the name of ETA Manufacture Horlogère Suisse discloses a timepiece oscillator, which includes a structure and distinct primary resonators, which are temporally and geometrically shifted, each comprising a weight returned towards the structure by an elastic return means. This timepiece oscillator includes coupling means for the interaction between the primary resonators, including driving means for driving in motion a wheel set which includes driving and bearing means arranged to drive and guide a control means articulated to transmission means each articulated, at a distance from the control means, to a weight of a primary resonator, and the primary resonators and the wheel set are arranged such that the articulation axes of any two of the primary resonators and the articulation axis of the control means are never coplanar.